The present invention relates to high pressure fuel pumps, and particularly to the inlet valve for feeding low pressure fuel to the high pressure pumping chamber.
Single piston and multi-piston high pressure common rail fuel pumps have been implemented to provide the high fuel pressures required by modern direct injected gasoline and diesel engines. These engine mounted pumps are volume controlled to minimize parasitic losses while maintaining rail pressure. Volume control is achieved either by inlet throttling using a magnetic proportional control valve, or indirect digital control of the inlet valve by a magnetic actuator. Either execution requires that the pump be controlled by an electrical signal from the engine ECU.
Because the indirect inlet valve actuator control requires a separate actuator for each pump piston, it has become common for multi-piston pumps to use a single inlet throttling proportional valve, in order to avoid a high part count and cost. Many modern single piston pumps use an indirect inlet valve actuator with a separate magnetically controlled armature assembly. These devices typically employ three separate components: inlet valve, magnetic armature, and the intervening engaging or connecting member. Different variants of this concept can be seen in U.S. Pat. Nos. 6,526,947, 7,513,240, 6,116,870, and 7,819,637. Due to the high complexity and precision of these devices, they typically account for at least ⅓ of the cost of a single piston pump. These digital type devices also suffer from high reciprocating mass and noise due to impact of the armature and valve assemblies during energizing and de-energizing events.